eCryptfs: Fix new inode race condition

Only unlock and d_add() new inodes after the plaintext inode size has
been read from the lower filesystem. This fixes a race condition that
was sometimes seen during a multi-job kernel build in an eCryptfs mount.

https://bugzilla.kernel.org/show_bug.cgi?id=36002

Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Reported-by: David <david@unsolicited.net>
Tested-by: David <david@unsolicited.net>

5 files changed, 30 insertions, 28 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index b8d5c8091024..f48c4987a15c 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1568,11 +1568,11 @@ out:
 }
 
 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
-                                            struct dentry *ecryptfs_dentry)
+                                            struct inode *inode)
 {
         int rc;
 
-        rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry->d_inode);
+        rc = ecryptfs_read_xattr_region(page_virt, inode);
         if (rc)
                 goto out;
         if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 41a453236371..72aa24a4c71e 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -662,7 +662,7 @@ void ecryptfs_write_crypt_stat_flags(char *page_virt,
 int ecryptfs_read_and_validate_header_region(char *data,
                                              struct inode *ecryptfs_inode);
 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
-                                            struct dentry *ecryptfs_dentry);
+                                            struct inode *inode);
 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes);
 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code);
 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat);
@@ -753,7 +753,7 @@ int ecryptfs_privileged_open(struct file **lower_file,
                              struct dentry *lower_dentry,
                              struct vfsmount *lower_mnt,
                              const struct cred *cred);
-int ecryptfs_get_lower_file(struct dentry *ecryptfs_dentry);
+int ecryptfs_get_lower_file(struct dentry *dentry, struct inode *inode);
 void ecryptfs_put_lower_file(struct inode *inode);
 int
 ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index 566e5472f78c..4ec9eb00a241 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -191,7 +191,7 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
                                       | ECRYPTFS_ENCRYPTED);
         }
         mutex_unlock(&crypt_stat->cs_mutex);
-        rc = ecryptfs_get_lower_file(ecryptfs_dentry);
+        rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
         if (rc) {
                 printk(KERN_ERR "%s: Error attempting to initialize "
                         "the lower file for the dentry with name "
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index fc7d2b748503..f0ad965d7d51 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -259,7 +259,8 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
                                 "context; rc = [%d]\n", rc);
                 goto out;
         }
-        rc = ecryptfs_get_lower_file(ecryptfs_dentry);
+        rc = ecryptfs_get_lower_file(ecryptfs_dentry,
+                                     ecryptfs_dentry->d_inode);
         if (rc) {
                 printk(KERN_ERR "%s: Error attempting to initialize "
                         "the lower file for the dentry with name "
@@ -350,50 +351,51 @@ static int ecryptfs_lookup_interpose(struct dentry *ecryptfs_dentry,
                        __func__, rc);
                 goto out;
         }
-        if (inode->i_state & I_NEW)
-                unlock_new_inode(inode);
-        d_add(ecryptfs_dentry, inode);
-        if (S_ISDIR(lower_inode->i_mode))
-                goto out;
-        if (S_ISLNK(lower_inode->i_mode))
-                goto out;
-        if (special_file(lower_inode->i_mode))
+        if (!S_ISREG(inode->i_mode)) {
+                if (inode->i_state & I_NEW)
+                        unlock_new_inode(inode);
+                d_add(ecryptfs_dentry, inode);
                 goto out;
+        }
         /* Released in this function */
         page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);
         if (!page_virt) {
                 printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",
                        __func__);
                 rc = -ENOMEM;
+                make_bad_inode(inode);
                 goto out;
         }
-        rc = ecryptfs_get_lower_file(ecryptfs_dentry);
+        rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
         if (rc) {
                 printk(KERN_ERR "%s: Error attempting to initialize "
                         "the lower file for the dentry with name "
                         "[%s]; rc = [%d]\n", __func__,
                         ecryptfs_dentry->d_name.name, rc);
+                make_bad_inode(inode);
                 goto out_free_kmem;
         }
         put_lower = 1;
-        crypt_stat = &ecryptfs_inode_to_private(
-                                        ecryptfs_dentry->d_inode)->crypt_stat;
+        crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
         /* TODO: lock for crypt_stat comparison */
         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
                         ecryptfs_set_default_sizes(crypt_stat);
-        rc = ecryptfs_read_and_validate_header_region(page_virt,
-                                                      ecryptfs_dentry->d_inode);
+        rc = ecryptfs_read_and_validate_header_region(page_virt, inode);
         if (rc) {
                 memset(page_virt, 0, PAGE_CACHE_SIZE);
                 rc = ecryptfs_read_and_validate_xattr_region(page_virt,
-                                                             ecryptfs_dentry);
+                                                             inode);
                 if (rc) {
                         rc = 0;
-                        goto out_free_kmem;
+                        goto unlock_inode;
                 }
                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
         }
-        ecryptfs_i_size_init(page_virt, ecryptfs_dentry->d_inode);
+        ecryptfs_i_size_init(page_virt, inode);
+unlock_inode:
+        if (inode->i_state & I_NEW)
+                unlock_new_inode(inode);
+        d_add(ecryptfs_dentry, inode);
 out_free_kmem:
         kmem_cache_free(ecryptfs_header_cache_2, page_virt);
         goto out;
@@ -403,7 +405,7 @@ out_put:
         d_drop(ecryptfs_dentry);
 out:
         if (put_lower)
-                ecryptfs_put_lower_file(ecryptfs_dentry->d_inode);
+                ecryptfs_put_lower_file(inode);
         return rc;
 }
 
@@ -843,7 +845,7 @@ static int truncate_upper(struct dentry *dentry, struct iattr *ia,
                 lower_ia->ia_valid &= ~ATTR_SIZE;
                 return 0;
         }
-        rc = ecryptfs_get_lower_file(dentry);
+        rc = ecryptfs_get_lower_file(dentry, inode);
         if (rc)
                 return rc;
         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
@@ -999,7 +1001,7 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
 
                 mount_crypt_stat = &ecryptfs_superblock_to_private(
                         dentry->d_sb)->mount_crypt_stat;
-                rc = ecryptfs_get_lower_file(dentry);
+                rc = ecryptfs_get_lower_file(dentry, inode);
                 if (rc) {
                         mutex_unlock(&crypt_stat->cs_mutex);
                         goto out;
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 7c697abab396..943a4f55ed6d 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -135,12 +135,12 @@ static int ecryptfs_init_lower_file(struct dentry *dentry,
         return rc;
 }
 
-int ecryptfs_get_lower_file(struct dentry *dentry)
+int ecryptfs_get_lower_file(struct dentry *dentry, struct inode *inode)
 {
-        struct ecryptfs_inode_info *inode_info =
-                ecryptfs_inode_to_private(dentry->d_inode);
+        struct ecryptfs_inode_info *inode_info;
         int count, rc = 0;
 
+        inode_info = ecryptfs_inode_to_private(inode);
         mutex_lock(&inode_info->lower_file_mutex);
         count = atomic_inc_return(&inode_info->lower_file_count);
         if (WARN_ON_ONCE(count < 1))